• Nuclear Engineering and Technology
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• v.38 no.6
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• pp.489-504
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• 2006

A review has been made for the previous studies on safety of a geologic repository for high-level radioactive wastes (HLW) related to autocatalytic criticality phenomena with positive reactivity feedback. Neutronic studies on geometric and materials configuration consisting of rock, water and thermally fissile materials and the radionuclide migration and accumulation studies were performed previously for the Yucca Mountain Repository and a hypothetical water-saturated repository for vitrified HLW. In either case, it was concluded that it would be highly unlikely for an autocatalytic criticality event to happen at a geologic repository. Remaining scenarios can be avoided by careful selection of a repository site, engineered-barrier design and conditioning of solidified HLW. Thus, criticality safety should be properly addressed in regulations and site selection criteria. The models developed for radiological safety assessment to obtain conservatively overestimated exposure dose rates to the public may not be used directly for the criticality safety assessment, where accumulated fissile materials mass needs to be conservatively overestimated. The models for criticality safety also require more careful treatment of geometry and heterogeneity in transport paths because a minimum critical mass is sensitive to geometry of fissile materials accumulation.

• Tunnel and Underground Space
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• v.4 no.3
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• pp.250-255
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• 1994

복잡한 지하구조인 지하터널과 핵폐기물 저장소 부지조사에 관한 자료해석을 위하여 지오토모그래피를 이용하였다. 지하터널의 조사는 지하저장소, 자원개발 및 군사적인 측면에서 많은 연구와 응용이 요구된다. 본 연구에서는 미육군이 현장에서 얻은 자료를 처리하고 이를 이론모형의 결과와 비교하였다. 또한 핵폐기물 부지 조사는 미국의 핵폐기물 저장소의 후보로 지정된 Yucca Mountain의 지질구조에 대한 이론모형계산을 행하였으며, Jaramillio(1993)가 모형실험치를 image 방법에 의하여 계산한 결과와 비교하였다. 탐사방법으로는 탄성파 시추공-시추공 방법과 VSP 방법을 사용하였다. 지오토모그래피의 기본이론은 터널과 지하공간 제3권 1호(1993)에서 설명되었다.

• Animal Bioscience
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• v.36 no.4
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• pp.540-554
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• 2023

Heat stress is a major challenge to animal production in tropical and subtropical climates. Rabbits suffer from heat stress more than farm animals because they have few sweat glands, and their bodies are covered with thick fur. Intensive farming relies on antibiotics as antimicrobials or growth promoters to increase animals' productivity and health. However, the European Union and many countries have banned or restricted the use of antibiotics in animal feed for human health concerns. Several studies have found that replacing antibiotics in rabbit feed with natural plants or feed additives increases productivity and improves immune capacity, especially under heat stress conditions. Growth performance, immune response, gut microflora, and carcass yield may be increased in rabbits fed a diet supplemented with some natural plants and/or propolis. In this review article, we discuss and summarize the effects of some herbs and plant extracts as alternative feed additives on rabbit productivity, especially for those raised under hot ambient temperatures.

• Korean Journal of Organic Agriculture
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• v.25 no.4
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• pp.901-916
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• 2017

This study was conducted to evaluate natural plant extracts for methane gas reduction in ruminants. Rumen fluid was collected from cannulated Hanwoo cow ($450{\pm}30kg$) consuming 400 g/kg concentrate and 600 g/kg timothy. The 15 ml of mixture comparing McDougall's buffer and rumen fluid in the ratio 2 to 1, was dispensed anaerobically into 50 ml serum bottles. Rumen fluid contents were collected and in vitro fermentation prepared control (timothy, 300 mg), ginseng, balloon flower, yucca plant, camellia, tea plant and ogapi extracts were added at the level of 5% against 300 mg of timothy as a substrate (v/w) and incubated for 3, 6, 9, 12, 24, 48, and 72 h. In vitro pH values range 6.55~7.41, this range include rumen titration. The dry matter digestibility was not differ between all treatments and control. Total gas emission was significantly higher (p<0.05) in ginseng and balloon flower treatments on 24 h than in control. Carbon dioxide emission was not differ all treatments on 9 h than in control and significantly higher (p<0.05) yucca plant, camellia and tea plant treatments on 12 h than control. Methane emission was not differ all treatments on 6 h than in control. The rumen microbial growth rate was significantly higher (p<0.05) in ginseng, balloon flower on 12 h and significantly higher (p<0.05) in ginseng, yucca plant, tea plant and ogapi treatments on 24 h than in control. Total VFA was significantly higher (p<0.05) in tea plant and ogapi treatments on 12 h than in control and significantly higher (p<0.05) in ginseng, balloon flower treatments on 48 h than in control. Acetic acid was significantly lower (p<0.05) in ginseng and balloon flower treatments on 24 h than in control. Propionic acid was significantly higher (p<0.05) in ginseng and balloon flower treatments on 48 h than in control. As a results, sixth natural plant extracts had no significant effect dry matter digestibility and negative on rumen fermentation, but not effect methane reduction.

• Asian-Australasian Journal of Animal Sciences
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• v.27 no.10
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• pp.1426-1435
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• 2014

Saponins have been considered as promising natural substances for mitigating methane emissions from ruminants. However, studies reported that addition of saponin-rich sources often arrived at contrasting results, i.e. either it decreased methane or it did not. The aim of the present study was to assess ruminal methane emissions through a meta-analytical approach of integrating related studies from published papers which described various levels of different saponin-rich sources being added to ruminant feed. A database was constructed from published literature reporting the addition of saponin-rich sources at various levels and then monitoring ruminal methane emissions in vitro. Accordingly, levels of saponin-rich source additions as well as different saponin sources were specified in the database. Apart from methane, other related rumen fermentation parameters were also included in the database, i.e. organic matter digestibility, gas production, pH, ammonia concentration, short-chain fatty acid profiles and protozoal count. A total of 23 studies comprised of 89 data points met the inclusion criteria. The data obtained were subsequently subjected to a statistical meta-analysis based on mixed model methodology. Accordingly, different studies were treated as random effects whereas levels of saponin-rich source additions or different saponin sources were considered as fixed effects. Model statistics used were p-value and root mean square error. Results showed that an addition of increasing levels of a saponin-rich source decreased methane emission per unit of substrate incubated as well as per unit of total gas produced (p<0.05). There was a decrease in acetate proportion (linear pattern; p<0.001) and an increase in propionate proportion (linear pattern; p<0.001) with increasing levels of saponin. Log protozoal count decreased (p<0.05) at higher saponin levels. Comparing between different saponin-rich sources, all saponin sources, i.e. quillaja, tea and yucca saponins produced less methane per unit of total gas than that of control (p<0.05). Although numerically the order of effectiveness of saponin-rich sources in mitigating methane was yucca>tea>quillaja, statistically they did not differ each other. It can be concluded that methane mitigating properties of saponins in the rumen are level- and source-dependent.

• The Korean Journal of Pesticide Science
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• v.10 no.3
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• pp.225-229
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• 2006

This study was conducted to screen herbicidal activity of Korean native plants which could be used for the development of new natural herbicides. Fifty-five plants were collected from Wan and Jeju islands in Korea and their methanol extracts were obtained. Herbicidal activity of methanol extracts were determined by seed bioassay using rape (Brassica napus L.) seedlings. Among fifty-five species, five plants were highly herbicidal ($GR_{50}$ < 1,000 ${\mu}g\;g^{-1}$): Clematis apiifolia A. P. DC.; (811 ${\mu}g\;g^{-1}$), Euscaphis japonica (THUNB.) KANITZ (867 ${\mu}g\;g^{-1}$), Hibiscus mutabilis L. (988 ${\mu}g\;g^{-1}$), Phyllostachys pubescens MAZEL (778 ${\mu}g\;g^{-1}$), Yucca recurvifolia (857 ${\mu}g\;g^{-1}$). Twenty-seven plants were shown moderately herbicidal (1,000 < $GR_{50}$ < 2,000 ${\mu}g\;g^{-1}$), however, twenty-three plants were not shown any herbicidal activity.

• The Korean Journal of Pesticide Science
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• v.8 no.3
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• pp.220-230
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• 2004

This study was conducted of Korean native plants to screen herbicidal activity which could be used for the development of new natural herbicides. Ninety-eight plants were collected from Wan Island, Chollanamdo in Korea and their methanol extracts were obtained. Herbicidal activities of the methanol extracts were determined by seed bioassay using canola (Brassica napus L.) seedlings. Among ninety-eight species, twenty plants were highly herbicidal ($GR_{50}<1,000\;{\mu}g\;g^{-1}$): Abies holophylla MAXIM., Ailanthus altissima (MILL.) SWINGLE, Anthemis nobilis L., Aralia elata SEEM., Artemisia iwayomogi KITAMURA, Asarum sieboldii MIQ., Brassica campestris subsp. napus var. nippo-oleifera MAKINO, Clematis terniflora DC., Crataegus scabrida SARG., Gnaphalium affine D. DON, Jasminum nudiflorum LINDL., Kalopanax pictus (THUNE.) NAKAI, Machilus japonica S. et Z., Myrica rubra S. et Z., Osmunda japonica THUNB., Phytolacca esculenta V. Houtte, Platanus occidentalis L., Quisqualis indica L., Rubus hirsutus THUNB., Yucca smalliana FERN. Fifty plants were shown moderate herbicidal activity $(1,000\;{\mu}g\;g^{-1}, however, twenty-eight plants were not shown any herbicidal activity.

• Journal of the Korean Society of Clothing and Textiles
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• v.32 no.9
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• pp.1366-1375
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• 2008

This studies were carried out in order to develope environmentally-friendly fiber materials and substitute resources of Paper mulberry. Various plant fibers such as New Zealand flax, Indian mallow, Kuzu vine and Yucca were used as raw materials of hand-made papers. We rotted these 4 kinds of plant fibers and removed non-cellulose. After rotting, the pulping rate(%) and the length of fibers in pulps were measured. The physical characteristics of papers made of various plants fiber were investigated and the probabilities of practical use were considered. The results were as follow: The non-cellulose contents of plant fibers were $30{\sim}40%$ and those contents must be lower down to 8% to be able to manufacture the hand made papers. The lignin in pulps were removed almost and the hemicellulose were partially removed to reach up to appropriate level of the pulp rates and fiber lengths. The more hemicellulose removed, the finer fiber thickness were and rapidly the lower Hanji tensile strength were. But the tear strength of these plants of hand-made papers do not decreased so much as tensile strength. So the property of 4 types of plant fibers might be of great advantages to make hand-made papers. Both tensile and tear strengths of Hanji of New Zealand flax, Indian mallow, Kuzu vine and Yucca were higher than Paper mulberry hand-made paper. When 30% of mulberry paper were mixed, the mixing effect showed maximum. Because of the functions of all plant fiber hand-made papers showed better than those of Paper mulberry hand-made paper, 4 types of plant fibers could be substitute Paper mulberry.

• The Journal of Engineering Geology
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• v.33 no.2
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• pp.335-353
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• 2023

Site selection processes for high-level radioactive waste disposal facilities in different countries differ in terms of local geology and degree of public engagement. There seem to be three alternative processes for site selection: (1) selection with community consent after government choice; (2) selection with continuous community engagement after exclusion of unsuitable areas based on existing survey data; or (3) site selection where communities have expressed a willingness to participate. The Yucca Mountain site in Nevada, USA, was selected as the final disposal site by process (1) through six stages, but its development was suspended owing to opposition from the local governor and environmental groups. In Sweden, Switzerland, and Germany, process (2) is used and sites are selected through three stages. Sweden and Switzerland have completed site selection, and Germany is currently engaged in the process. The UK adopted process (3) with six stages, although the process has been suspended owing to poor community participation. In Korea, temporary storage facilities for spent nuclear fuel will reach saturation from 2030, so site selection must be promoted through various laws and systems, with continuous communication with local communities based on transparent and scientifically undertaken procedures.

• Journal of the Korean Home Economics Association
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• v.29 no.2
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• pp.1-15
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• 1991

The purpose of this study was to understand the diversity and speciality of Aztec dress which has not been well known, and to overcome ethnocentrism in clothing perceptions. From 15 century to early 16 century, the Aztec empire based on the unique view of the world, most flourished in Mesoamerica. Ritualistic and official side of Aztec life was reflected well on dress. Most Aztec garments consisted of unsewn pieces of cloth, draped on the body as loincloth, mantle and wraparound skirt. Slightly more complicated garments such as women's blouses(huipils) and men's simple jackets were created by sewing together two or more pieces of material. In the sharply stratified world of Aztec, strict sumptuary laws controlled dress. The garments of lower classes were made of maguey or yucca fiber, and only the upper classes were allowed to wear cotton clothing. In addition to material, color, elaborateness and even manner of tieing the mantle were carefully controlled by government edict. As the Aztec empire expanded and became wealthier, the sumptuary laws could not actually dictate what people wore everyday but rather provided a set of rules governing clothing for ceremonial occasions. Aztec's warrior costumes, consisted of headdress, towering back devices, feather garments, were sufficient to suggest the theatrical grandeur of what must have been one of the most magnificiently attired armies ever assembled.